PVMBG reported visual monitoring of Sinabung during 1-17 June from the Ndokum Siroga village (~8.5 km of the summit). Dome growth continued and was accompanied by a lava flow that was frequently visibly incandescent. The observatory noted that the lava flow (particularly avalanches from the flow front) presented a threat to areas S and SE within a 5 km radius from the summit. During this reporting period, seismicity was dominated by tremor associated with avalanches, and there was minor deformation. Alert Level 3 was maintained (on a scale of 1-4).

Geological Summary. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. The youngest deposit is a SE-flank pyroclastic flow 14C dated by Hendrasto et al. (2012) at 740-880 CE. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)